Continuous tube forming and galvanizing



June 21, 1966 T, H. KRENGEL ETAL 3,256,592

CONTINUOUS TUBE FORMING AND GALVANIZING ODMQWMM ATT'Ys June 21, 1966 T.H. KRENGEL r-:TAL 3,256,592

CONTINUOUS TUBE FORMING AND GALVANIZING 2 Sheets-Sheet 2 Filed Jan. 15,1964 INVENTORS 'THEODORE H KRENGEL cmd EM-LL WILK 0 M7 'l ATTYs UnitedStates Patent O 3,256,592 CONTINUGUS TUBE FORMING AND GALVANIZINGTheodore H. Krengel, Chicago, and Emil Wilk, Park Forest, lll.,assignors to Allied Tube & Conduit Corporation, Harvey, lll., acorporation of Illinois Filed Jan. 15, 1964, Ser. No. 337,948 3 Claims.(Cl. 29-200) This invention relates to a continuous process for formingand galvanizing tubing of endless strips of steel and it relates moreparticularly to the processing of endless strips of steel to formtubing'in a continuous operation and in the treatment of the externalsurfaces of the formed tubing for galvanizing as a continuous operationin combination with tubing formation.

This is a continuation-in-part of application Ser. No. 106,699, filedMay 1, 1961, entitled Continuous Tube Forming and Galvanizing, now U.S.Patent No. 3,122,- 114, issued February 18, 1964.

It is an object of this invention to provide a new and improved processfor the continuous forming of tubing from endless lengths of strip steeland for continuous galvanizing of the formed tubing as a continuousoperation with the formation of the tubing and it is a related object toproduce a new and improved machine for use in the practice of same.

Another object is to provide a machine and process for the continuousforming and galvanizing Iof tubing from sheet steel in a simple andefiicient manner to produce a galvanized tubing at less cost from thestandpoint of labor, from the standpoint of material utilization andcost, from the standpoint of space requirements, and from the standpointof heat and power requirements, and it is a related object-to produceand to provide a method for producing galvanized tubing having improvedcharacteristics and appearance without substantial variation in suchcharacteristics and appearance between lengths.

These and other objects and advantages of this invention willhereinafter appear and, for purposes of illustration, but not oflimitation, an embodiment of the `invention is shown in the accompanyingdrawings in which:

FIG. 1 is a schematic flow diagram of the continuous forming andgalvanizing of tubing in accordance with the practice of this invention;

FIG. 2 is a sectional elevationalview of the furnace for the continuousgalvanizing ofthe formed tubing in accordance with the practice of thisinvention;

FIG. 3 is a sectional View taken substantially along the line 3-'3 ofFIG. 2;

FIG. 4 is a sectional elevational view taken substantially along theline 4-4 of FIG. 3;

FIG. 5 is a sectional view taken substantially along the line 5 5 ofFIG. l;

FIG. 6 is a sectional view taken substantially along the line 6 6 ofFIG. l; and

FIG. 7 is a schematic elevational view of a fragmentary portion of thetube forming apparatus illustrating the arrangement of elements forwelding the tubing.

Since the important concepts of this invention reside in the method andmeans for the continuous forming and galvanizing of tubing by theprocessing of endless lengths and strip steel, the invention will bedescribed with .reference to a continuous process for forming the metaltubing and in the processing of the formed tubing in a galvanizing,sizing and shearing operation for cutting the nished tubing intodesirable lengths.

Referrring now to FIG. 1 of the drawings, the tubing forming mill is fedwith strip steel 10 supplied in the form of coils 12 mounted on apay-out reel 14 for free rotationl azaasaa Patented June 2l, 1966 almovement to pay out strip steel as it is required by the continuous tubeforming mill. In a continuous mill for forming tubing, the strip steelis processed substantially continuously at a relatively constant ratethrough the mill. Advancement is effected primarily by engagementbetween the strip steel and the forming and sizing rolls rotating atrelatively constant speed whereby the strip steel is drawn into the millfor processing.

Since the lengths of the steel strip in the coils 12 come to an endafter a short period of operation of the mill and since strip is takenup continuously by the mill in its continuous operation, it is essentialto provide mean-s for splicing the end of one coil 16 with the leadingend 18 of another lcoil for joinder of the strips into continuouslengths without stoppage of the mill in its continuous operation. Forthis purpose, a loop 20 is taken in the rstrip of steel dimensioned tohave a length sufficient continuously to feed strip to the mill whilethe trailing end 16 of the strip is stationarily held for splicing, asby Welding, onto the leading edge of the new reel which has beendisplaced into position of use. The loop is formed by feeding the strip10 under the roller 22 and over the roller 24 to about the roller 26 andback over the roller 28 and under the roller 30 into the mill. Therollers are each mounted for free rotational movement while the roller26 is carried by a carriage 32 having wheels 34 rotatably positionedupon a track 36 for endwise displacement of the carriage in onedirection to make strip available to the mill and in the otherdirection, responsive to the actuation Iof the winch 38 through thecable 40, to return the carriage and to reform the loop.

Normally, the carriage is in its retracted position to provide a fullloop 20 of strip steel which rests upon a platform 42 overlying the milland underlying the track. When the end is reached, a portion adjacentthe end is l-ocked in a clamping member 44 to hold the end section whilethe end 16 of the coil is joined, as by welding, to the beginning of thenext coil in the joiner 46. The operation takes but a few seconds. Inthe meantime, the mill continues to draw its requirements of strip fromthe loop to displace the carriage 32 in the direction away from thewinch as the loop is shortened. When the ends of the coils have beenjoined, the clamping device 44 is inactivated to free the strip wherebystrip can thereafter be supplied from the new coil as the winch 38 andcable 40 are effective to return the carriage to normal retractedposition and replenish the loop in preparation for the next splicingoperation. It will be apparent that the strip 10 feeds from the coilthrough the loop to the mill for continuous operation.

Hereafter description will be made of the sequence of operationseffected in the mill with the elements in the mill longitudinallyaligned for the passage of strip and the tubing formed thereofcontinuously linearly therethrough. In the preferred prac-tice, thestrip 10 is dimensioned to be slightly greater in width than is requiredto form the tubing so that an edge can be made available from each sideto be shaved therefrom in sizing the strip and to provide freshly cutmetal in the meeting edges forming the seam thereby t-o enhance joinderas by a continuous welding operation to'form the closed tubing. From theedge shaver 45 the strip is advanced to wiper 47, such for example as apad, which sweeps or otherwise removes chips or other pieces of metalreleased from the shaving operation. This operation has not heretoforebeen employed in the continuous formation of galvanized thin Walltubing, yetfailure to remove such metal particles from the surface ofthe metal strip has been found to leave the metal particles where theycan become bonded to the surface during subsequent processing steps,such as heating, welding, galvanizing and the like, to constitute anobstruction in the interior of the formed tubing and to provideundesirable surface roughness. Instead of a wiper pad, the looseparticles can be removed by a blow-off jet, etc. From the cleaning stage47, the strip enters a series of aligned conventional tube formingrolls, identified by the numeral 48, whereby the strip is deformed froma flat section to a rounded tubing having the freshly cut edges of thestrip in abutting relation to form the seam of the tubing.

From the tubing forming roll section 48, the `formed tubing is advanceddirectly to the seam Welder 50 where the abu-tting free edges of thestrip formed to tubular shape are joined by Welding, preferably using acontinuous resistance Welder in order to keep the upset on the inside ofthe formed tubing at a minimum. Otherwise, it would require the use of asupport within the tubing and/ or an upset removing tool employed incombination with a water suction device. Since sufficient space is notavailable in small diameter tubing for housing such support, upsetremoval tool and water suction means, it has been found t-o beexpedient, in accordance with the practice of this invention, to makeuse of a continuous Welder in the form of a roller adjusted to effectthe major upset on the outside of the tubing where access is availablefor removal.

It has been conventional practice to apply cooling water to the entryend of the welding operation for purposes of cooling the electrode.However, it has been found that the application of cooling water beforethe seam has been closed enables water to gain access to the interior ofthe formed tubing, where, in the continuous tube forming and galvanizingprocess described and claimed by applicants, it can raise numerousproblems, as by vaporization of the water at the high temperatures towhich the tubing is exposed during the subsequent galvanizingoperations. As a result, as a further irnprovement in the process ofcontinuous forming and galvanizing of thin wall tubing, the coolant isapplied directly onto the cylindrical welding electrode in the portionimmediately after it leaves the surface of the tubing, or the nineoclock position, so that by the time that the wetted portion travelsaround to again come into Welding engagement with the oncoming tubing,it has had time to dry from the applied cooling medium. Thus the coolantis applied onto the electrode aligned with the trailing portion of thewelding operation wherein the same has already been closed and water isincapable of finding its way into the formed tubing. Cooling of theelectrode remains efficient even with the described transformation.

When, as in the practice of this invention, the upset is concentrated onthe outside, the upset or flash can be removed by a `seam shaving tool52 which follows immediately after the seam Welder. The seam shaverembodies a scarng tool which shaves the seam to leave a smooth surfaceon the outer periphery of the formed tubing and whereby the seam wouldbe concealed except for the presence of a heat line indicated by a darkdiscoloration of metal oxide formed along the weld surface.

By way of a still further improvement in the means and 4method for thecontinuous forming of galvanized thin wall tubing, it has been found tobe desirable to quench the hot surface of the tubing immediately afterthe scarfing operation to minimize oxidation of the freshly cut and hotsurface. For this purpose, cold water is applied t-o the surface of thetubing 53 immediately after the scarfing operation with the result thata heat treating effect to produce a blue coloration indicative of ametallic surface free of oxidation is secured, as distinguished from anotherwise formed brownish discoloration on the freshly cut surface,indicative of oxide formation. This minimum film secured by watercooling of the freshly cut hot -metal surface can be easily removed bythe subsequent cleaning fiuids whereas the otherwise formed oxide filmis incapable of removal sufficiently cleanly to permit the formation ofa desired zinc coating during the subsequent galvanizing step.

To this point, welded tubing is continuously formed of strip steel withthe exception of the possible short lengths of formed tubing whichremain with an open seam in the event of skidding of the tubing and themachine when Ithe mill is stopped for one reason or another. As aresult, in the described continuous processing for forming tubing, anauxiliary Welder 54 in the form of a heliarc Welder may be employed,Where desired, to take over the welding operation whenever the seamWelder fails to weld the seam of the formed tubing. When employed, anoverlap is effected with the stop and start of the mill continuously toweld the seam and to insure closure of the seam' throughout the lengthof the tubing. In actual practice with good controls, it has been foundthat the heliarc Welder is not essential.

After the tubing has been welded to provide a continuous weld throughoutthe length thereof, the tubing is advanced from the Welders to elementslinearly aligned therewith for washing and pickling the outer surfacesof the formed tubing in preparation for continuous galvanizing. Thewelded tubing 56 is advanced first into a housing 58 having a removablecover 60 for access thereto. The housing is provided with a plurality ofaxially aligned ring members 62 in the form of headers having aplurality of spray nozzles 64 arranged equally spaced about the innerperiphery for directing a spray 66 onto the outer periphery of thetubing 56 advanced axially therebetween. Each spray head is connected toa reservoir 68 of Wash water for recirculating the wash water from thereservoir through pipe 70 to the spray head 62 and from the drain in thehousing back through pipe 72 for return to the reservoir. In theillustrated modification the reservoir is shown alongside the housingbut it may equally be arranged in other positons such as beneath thehousing. A pump means is interposed between the reservoir and the sprayheads for displacement of wash water forcibly to spray the wash wateronto the exposed surfaces of the tubing as it passes through thehousing. For purposes of washing to remove grease and the like, use canbe made of an alkali wash which may be represented by a solution of 5ounces of alkali per gallon of Water and it is preferred to heat thewash water to a temperature below the boiling point of the alkalisolution, such as to a temperature of 200 F. to accelerate removal ofgrease from the surface.

From the hot alkali wash, the tubing 56 is advanced continuously intothe adjacent section of housing 74 in which the tubing is treated with adilute alkali Wash. The housing 74 is similar to that of the housing 58for the hot alkali wash including spray heads to direct the dilutealkali wash onto the periphery of the tubing and with a separatereservoir 76 connected to the headers to feed dilute alkali from thereservoir to the headers and connected to the drain in the base of thehousing for returning the dilute alkali wash from the housing back tothe reservoir. The dilute alkali wash is employed for more completeremoval of grease and dirt from the surface of the tubing and the use ofthe dilute alkali wash following immediately after the strong alkaliwash operates to save alkali loss since strong alkali carried on thesurface of the tubing from the strong alkali wash will be recovered inthe wash with dilute alkali to supply some of the alkali for maintainingthe desirable concentration thereof. The dilute alkali wash'may beformulated to contain about 2 ounces of alkali per gallon and it mayalso be heated to an elevated temperature such as to a temperature belowboiling, or up to 200 F. more effectively to remove grease and otherundesirable material from the surface of the welded tubing.

From the alkali washes the tubing is advanced into a rinse housing 78aligned endwise with the alkali wash housing and similarly constructed.The rinse housing is fitted with a number of axially aligned sprayheads,

similar to the rings employed in the alkali wash systems, from whichrinse water is sprayed onto the surface of the tubing as it passestherethrough to rinse remaining alkali from the surface before passingthe tubing into the pickling bath. The .rinse water is circulated underpressure from a water supply source to the spray heads and the watercollected in the bottom of the rinse housing can be released to thedrain unless water is at a premium, in which event the water isrecirculated with suicient makeup water to provide for substantialremoval of alkali. The rinse water may be used either cold or warm, butis economically undesirable to invest in warming the water unless thewarm water is recirculated between the housing and a water storagereservoir for re-use.

From the rinse', the tubing 56 is advanced directly into a picklinghousing 80 of similar construction as the wash and rinse housings andseparated therefrom only by a separating wall 82. The pickling housingis provided with a pair of longitudinally arranged, laterally spacedapart spray pipes 84 arranged in the upper portion of the housing tooverlie the tubing 56 which passes linearly through an intermediateportion of the housing beneath the spray pipes to face the weld seam inthe direction of the pipes. The pipes are each provided with a pluralityof spray nozzles 86 in the underside positioned to direct the spray 88angularly downwardly to converge on the weld seam positioned uppermostin the tubing passing therethrough. Thus the spray is directedforcefully from the spray nozzles onto the seam to react with the oxideson the surface which are formed at the weld. Use can be made ofconventional pickling solutions for removal of the metal oxide, such forexample as an acid solution containing about 30 percent by volume HC1dissolved in aquey ous medium. For best results, it is desirable to makeuse of a pickling solution heated to an elevated temperature such as ata temperature of 100-120 F., but a heated pickling solution is notessential.

The solution is stored in a suitable reservoir 90 and is connected withthe spray heads through lines 92 and 94 and circulation is effected bymeans of a displacement pump. The reservoir, pump and housing are allprovided with a rubber lining to protect the metal parts from the acidsof the pickling solution.

From the pickling housing 80, the pickled tubing is advanced into analigned section of housing 96 for rinsing the pickling solution from thesurface of the tubing. T-he rinse housing following pickling is verysimilar to the rinse housing 76 wherein water is sprayed from sprayrings onto surfaces of the tubing passing therethrough to rinse thepicklin g solution from the surface.

In the aforementioned alkali washes, rinse, pickling and final rinse,the housings can be of a unitary construction subdivided into separatesections by separating walls each of which is provided with alignedopenings dimensioned to enable the tubing to pass lengthwisetherethrough in and out of the housings. Instead, the housings can beseparated members with aligned openings in the end walls for thecontinuous passage of the tubing from one to another without bending.

- An important concept of this invention resides in the means and methodfor continuously galvanizing the formed tubing as a continuous operationwith the described forming, welding and cleaning operations. For

this purpose, it is desirable to contact the cleaned sur-A face of thesteel tubing with molten zinc for sufficient time to enable the desiredreact-ions to take place to form the desired thickness of galvanize onthe surface and it is irnportant to carry out the reactions undernon-oxidizing conditions, otherwise undesirable oxides of the metal willform at the elevated temperatures under which the re- -actions arecarried out.

The desired reducing or non-oxidizing atmosphere can be maintained bythe enclosure of the galvaniz-ing zone within a sealed housing intowhich an inert, or reducing gas can be introduced for maintenance of anon-oxidizing atmosphere. This can be accomplished by a sealed enclosurebut it is preferable to make use of an enclosure which is capable ofremoval to gain access to the interior of the galvanizing zone butwithout interfering with the ability to .achieve atmospheric control,when in position of use.

The desired characteristics have been achieved in the constructionillustrated in FIG. 13 of the drawings -by the use of a rectangular hood100 having a horizontally disposed top wall 102, side and end walls 104which depend perpendicularly downwardly from the edges of the top wallinto .a trough 106 facing upwardly from a frame 108 which extends allabout the galvanizing zone. The bottom edges 110 of the side walls arereceived within the trough for support of the hood on the bottom wallthereof. The trough is at least partially filled with `a pulverulentmaterial 112, such as tine sand, into which the lower edge of the sidewalls become embedded to effect a seal- -ing relationship all aroundlwhich militates against the ow of free gases all around for atmosphericcontrol. One or more inlets 114 for the inert or reducing gas areprovided in the walls of the hood for introduction of such inert orreducing gases in amounts tornaintain .an nonoxidizing atmospheretherein.

It has been found that the galvanizing reactions can becarried out morerapidly with greater uniformity when the tubing is preheated to anelevated temperature, such as -to .a temperature above the melting pointtemperature for the zinc, such as at 750 F., before being contacted withthe molten zinc, although it is not essential to preheat. Whenpreheating is effected, it is again important to achieve the desiredpreheat without exposure of the metal surface to oxidizing conditions,'otherwise the metal oxides that would form at an accelerated rate whilethe tubing is heated to an elevated temperature would interfere with theformation of a suitable galvanize on the surface. In the illustratedmodification, the preheat section comprises a tubular -housing 116 whichhas its center .aligned with the line of travel of the formed tubinglthrough the machine and which communicates with the enclosure 100.Inert gas is introduced into the tubular housing through an inlet 118 inthe forward end of the tubular mem-ber for the circulation of the inertor reducing gas lengthwise through the housing into the hood orenclosure 100 to maintain non-oxidizing conditions within the 4tubularhousing during passage of the tubing therethrough.

The tubing can be heated to elevated temperature by the introduction ofheat from suitable and conventional internal or external heaters lbut itis preferred to make use of induction heating means 120 within thetubular housing to accelerate the build-up of temperature Within thetubing walls in minimum time thereby to minimize the lengths necessaryfor the tubular housing.

Having described the preheat of the tubing and the introduction of thepreheated tubing into the inert galvavdisposed housing 122 in the formof a trough Valigned axially with the line of travel of the tubing forpassage of the tubing axially through an intermediate section of thehousing from an inlet 124 at one end to the outlet 126 at the oppositeend. The housing is provided with one or more inlets 128 which areconnected by a passage 130 to a reservoir 132 of molten zinc with meansfor displacement of the molten zinc from the reservoir to the inlets atarate suicient to maintain the housing substantially filled with moltenzinc to cover the tubing advanced therethrough. The inlet 128 ispreferably, though not necessarily, located in the portion of thehousing adjacent the inlet end 124 through which the tubing isintroduced into the housing for concurrent flow of the molten zincthrough the housing with the tubing and in position to overlie thetubing so as to direct the stream or streams of molten zinc onto thetubing.

The housing is further provided with a drain opening 180 in the bottomwall 182 of the housing with a downpipe 184 leading from the drain tothe reservoir. The drain opening is of small dimension to enable a thinstream of molten zinc constantly to ow therethrough but at a rate thatis considerably less than the rate of introduction of molten zinc intothe housing less the amount that escapes through the openings so thatthere will be an overow of molten zine over the ends of the troughforming the inlet and outlet to the housing Ibut with `an amount ofmolten zinc in the trough to cover the tubing passing therethrough. Thedrain opening 180 is effective in the event of some failure in operationor stoppage of the machine thereby to drain molten zinc from the housingbefore the zinc has cooled to a temperature below its melting point,otherwise the zinc would become solidified within the housing andthereby render the housing unfit for future use until the solidifiedzinc is passed from the housing or otherwise, with difficulty removed.

The zinc in the reservoir can be heated by suitable burners or otherheating means to maintain the zinc in the bath at a temperature aboveits melting point temperature of about 750 F. and preferably at atemperature above about 850 F. Access means are provided in the hood100` for addition of pigs of zinc to the reservoir in amountscorresponding to the zinc that is used or otherwise removed with thetubing.

It is important to provide a sufficient weight of coating of molten zinconto the surface of the formed tubing but it is undesirable to enableexcess molten zinc to be carried off with the tubing thereby to increasethe cost of galvanizing and/or prevent bead formation by excess zincremaining on the outer surface. One means particularly adapted tocontrol the thickness of the zinc coating without bead formation and toprovide for removal of excess for return to the reservoir, while in amolten state and while still in a protective atmosphere, comprises anelongate block 150 of stainless steel or ,the like formed with a groove152 extending lengthwise across the top wall 154 in which at least theleading edge portion 156 of the block still extends into the trailingend portion of the hood. The groove 152 in the top surface of the blockis adapted to corresponding in curvature with a hemispherical section ofthe tubing to engage the lower half thereof during passage of the tubinglengthwise therethrough. In the preferred practice, the groove is formedto a diameter corresponding to that of the tubing or slightly greater.

Cooperating with the block is a roller 158 mounted for rotationalmovement about an axis crosswise of the line of travel of the tubingwith an annular, arcuate recess 160 formed in the periphery of theroller shaped to correspond somewhat to a hemispherical section of thetubing being processed. As in the block, the arcuate recess 160 isdimensioned to have a diameter corresponding to that of the tubing orslightly greater. The roller is positioned with its lower edge 162 inendwise alignment with the top side of the recess 152 to more or lessdefine :a circular section therebetween corresponding to the (circularsection defined by the tubing or slightly greater.

Thus the roller 158 operates to engage the top side 'of the tubing afterit issues from the galvanizing trough to preposition the tubing both inits travel through the galvanizing system and for its subsequentengagement with the grooved block for wiping excess molten zinc from thesurface. Some excess zinc will also be removed by the roller uponengagement.

The cooperation between the roller and the block is believed to make theblock effective as .a wiper for removal `of excess molten zinc from the0111er wall of the tubing.

Such excess zinc is removed while the tubing is still within the hoodthereby to provide premature freezing of the metal while simultaneouslyprotecting the molten metal from oxidation so that the excesses removedcan be allowed to tiow back into the reservoir for re-use.

The block is effective to still leave a desirable amount of zinc as acoating on the outer wall of the tubing. To prevent ow and beadformation, it is desirable to freeze the metal as soon afterl wiping aspossible. For this purpose, use can be madeof a water quench, as in theform of a water spray or flow coat 164 following substantiallyimmediately after the tubing emerges from the hood.

From the galvanizing section, the galvanized tubing is advancedsequentially through a series of water spray sections to cool down thegalvanized tubing if the tubing has not otherwise been sufficientlycooled in the freezing step, and, from the cool-down operation, toconventional tube sizing rolls 192, and from the tube sizing rolls to atraveling shear section 194 where the endless tubing is cut into lengthsof predetermined dimension for shipping. The water spray sections aresimilar to the rinse sections which follow alkali cleaning or acid etchand the tube sizing rolls and flying shear are of conventionalconstruction.

As an alternative, the galvanized tubing, after being cooled, may beprocessed through a spray housing similar to the alkali cleaning,wherein the galvanized surface is wetted with a chromate and nitric acidsolution for reaction to form a surface of zinc chromate whereby stillgreater resistance to oxidation is secured by comparison with a plainzinc galvanized surface. If a section of the spray housing is devoted tothe chromate spray, an additional section should be provided for a waterrinse to remove excess chromate solution from the surface.

As another innovation, the tubing is marked, as by means of a markingroll, after galvanizing as distinguished from the conventional practiceof indenting to mark the tubing before galvanizing or even before theformation of the tubing. This is because the marking applied to thesurface of the tubing before galvanizing becomes lled with molten zincso that it would no longer be visible and the marked depressionsappeared also to interfere with the proper galvanizing of the tubingsurface. Thus the marking roll precedes tube sizing, as indicated by theposition 191.

It will be apparent from the foregoing description that I have provideda simple, efficient and effective means for continuously forming tubingof strip steel and for galvanizing the formed tubing as a continuousoperation with the continuous tube Vforming process.

It will be understood that changes may be made in the details ofconstruction, arrangement and operation, as well as in materialsemployed, without departing from the spirit of the invention, especiallyas defined in the following claims.

We claim:

1. In a machine for the continuous forming and galvanizing of tubingincluding means for continuously feeding the endless strip of steel tothe machine, means for forming the strip steel into rounded shape tobring the lateral edges together, welding means for joining the freeedges of the strip steel in a continuous seam to form completelyenclosed endless lengths of tubing, scarfing means for removing portionsextending outwardly from the periphery of the tubing, washing andcleaning means for removal of grease and dirt from the outer surfaces ofthe formed tubing, means for treating the outer surface of the formedtubing to remove metal oxides, means for applying molten zinc onto thesurface of the cleaned tubing and means for cutting the endless tubinginto predetermined lengths, the improvement wherein the welding meanscomprises a welding member in the form of a fiat circular disc memberhaving its lower peripheral edge portion in welding engagement with theupper side of the formed tubing to Weld the edges together to seal thetubing, means for rotating the disc member for displacement of the lowerperipheral edge adjacent the tubing in the direction of linear movementof the tubing, and means for applying a coolant liquid onto the portionof the disc member immediately after it leaves the tubing and in aportion overlying the welded portion of the tubing, and rotating theelectrode at a rate to enable the coolant liquid to drain from theelectrode before returning into Contact with the tubing.

2. A machine as claimed in claim 1 in which the coolant is applied atabout the nine oclock position on the welding disc.

3. A machine as claimed in'claim 1 in which the coolant is water.

References Cited by the Examiner UNITED STATES PATENTS CHARLES W.LANHAM, Primary Examiner.

R. J. HERBST, Assistant Examiner.

1. IN A MACHINE FOR THE CONTINUOUS FORMING AND GALVANIZING OF TUBINGINCLUDING MEANS FOR CONTINUOUSLY FEEDING THE ENDLESS STRIP OF STEEL TOTHE MACHINE, MEANS FOR FORMING THE STRIP STEEL INTO ROUNDED SHAPE TOBRING THE LATERAL EDGES TOGETHER, WELDING MEANS FOR JOINING THE FREEEDGES OF THE STRIP STEEL IN A CONTINUOUS SEAM TO FORM COMPLETELYENCLOSED ENDLESS LENGTHS OF TUBING, SCRAFING MEANS FOR REMOVING PORTIONSEXTENDING OUTWARDLY FORM THE PERIPHERY OF THE TUBING, WASING ANDCLEANING MEANS FOR REMOVAL OF GREASE AND DIRT FROM THE OUTER SURFACES OFTHE FORMED TUBING, MEANS FOR TREATING THE OUTER SURFACE OF THE FORMEDTUBING TO REMOVE METAL OXIDES, MEANS FOR APPLYING MOLTEN ZINC ONTO THESURFACE OF THE CLEANED TUBING AND MEANS FOR CUTTING THE ENDLESS TUBINGINTO PREDETERMINED LENGTHS, THE IMPROVEMENT WHEREIN THE WELDING MEANSCOMPRISING A WELDING MEMBER IN THE FORM OF A FLAT CIRCULAR DISC MEMBERHAVING ITS LOWER PERIPHERAL EDGE PORTION IN WELDING ENGAGEMENT WITH THEUPPER SIDE OF THE FORMED TUBING TO WELD THE EDGES TOGETHER TO SEAL THETUBING, MEANS FOR ROTATING THE DISC MEMBER FOR DISPLACEMENT OF THE LOWERPERIPHERAL EDGE ADJACENT THE TUBING IN THE DIRECTION OF LINEAR MOVEMENTOF THE TUBING, AND MEANS FOR APPLYING A COOLANT LIQUID ONTO THE PORTIONOF THE DISC MEMBER IMMEDIATELY AFTER IT LEAVES THE TUBING AND IN APORTION OVERLYING THE WELDED PORTION OF THE TUBING, AND ROTATING THEELECTRODE AT A RATE TO ENABLE THE COOLANT LIQUID TO DRAIN FROM THEELECTRODE BEFORE RETURNING INTO CONTACT WITH THE TUBING.